Make TCP connect() handle EINTR correctly

According to the POSIX standard, if connect() is interrupted by a signal that is caught while blocked waiting to establish a connection, connect() shall fail and set errno to EINTR, but the connection request shall not be aborted, and the connection shall be established asynchronously. If asynchronous connection was successfully established after EINTR and before the next connection attempt, OS returns EISCONN that was handled as an error before. This behavior is fixed now and we handle it as success. The problem affects MacOS users: Linux doesn't return EISCONN in this case, Windows connect() can not be interrupted without an old-fashoin WSACancelBlockingCall function that is not used in the library. So current solution gives connect() as OS specific implementation.
rust-lang · bors · Oct 19, 2023 · Oct 5, 2023 · Oct 13, 2023 · dfadd177a9738de289a3a6d4b39c08d94f384c1a
commit dfadd177a9738de289a3a6d4b39c08d94f384c1a
diff --git a/library/std/src/sys/hermit/net.rs b/library/std/src/sys/hermit/net.rs
@@ -56,6 +56,12 @@ impl Socket {
         unimplemented!()
     }
 
+    pub fn connect(&self, addr: &SocketAddr) -> io::Result<()> {
+        let (addr, len) = addr.into_inner();
+        cvt_r(|| unsafe { netc::connect(self.as_raw_fd(), addr.as_ptr(), len) })?;
+        Ok(())
+    }
+
     pub fn connect_timeout(&self, addr: &SocketAddr, timeout: Duration) -> io::Result<()> {
         self.set_nonblocking(true)?;
         let r = unsafe {

diff --git a/library/std/src/sys/solid/net.rs b/library/std/src/sys/solid/net.rs
@@ -233,12 +233,15 @@ impl Socket {
         }
     }
 
+    pub fn connect(&self, addr: &SocketAddr) -> io::Result<()> {
+        let (addr, len) = addr.into_inner();
+        cvt(unsafe { netc::connect(self.0.raw(), addr.as_ptr(), len) })?;
+        Ok(())
+    }
+
     pub fn connect_timeout(&self, addr: &SocketAddr, timeout: Duration) -> io::Result<()> {
         self.set_nonblocking(true)?;
-        let r = unsafe {
-            let (addr, len) = addr.into_inner();
-            cvt(netc::connect(self.0.raw(), addr.as_ptr(), len))
-        };
+        let r = self.connect(addr);
         self.set_nonblocking(false)?;
 
         match r {

diff --git a/library/std/src/sys/unix/net.rs b/library/std/src/sys/unix/net.rs
@@ -6,6 +6,7 @@ use crate::net::{Shutdown, SocketAddr};
 use crate::os::unix::io::{AsFd, AsRawFd, BorrowedFd, FromRawFd, IntoRawFd, RawFd};
 use crate::str;
 use crate::sys::fd::FileDesc;
+use crate::sys::unix::IsMinusOne;
 use crate::sys_common::net::{getsockopt, setsockopt, sockaddr_to_addr};
 use crate::sys_common::{AsInner, FromInner, IntoInner};
 use crate::time::{Duration, Instant};
@@ -140,6 +141,22 @@ impl Socket {
         unimplemented!()
     }
 
+    pub fn connect(&self, addr: &SocketAddr) -> io::Result<()> {
+        let (addr, len) = addr.into_inner();
+        loop {
+            let result = unsafe { libc::connect(self.as_raw_fd(), addr.as_ptr(), len) };
+            if result.is_minus_one() {
+                let err = crate::sys::os::errno();
+                match err {
+                    libc::EINTR => continue,
+                    libc::EISCONN => return Ok(()),
+                    _ => return Err(io::Error::from_raw_os_error(err)),
+                }
+            }
+            return Ok(());
+        }
+    }
+
     pub fn connect_timeout(&self, addr: &SocketAddr, timeout: Duration) -> io::Result<()> {
         self.set_nonblocking(true)?;
         let r = unsafe {

diff --git a/library/std/src/sys/windows/net.rs b/library/std/src/sys/windows/net.rs
@@ -140,13 +140,15 @@ impl Socket {
         }
     }
 
+    pub fn connect(&self, addr: &SocketAddr) -> io::Result<()> {
+        let (addr, len) = addr.into_inner();
+        let result = unsafe { c::connect(self.as_raw(), addr.as_ptr(), len) };
+        cvt(result).map(drop)
+    }
+
     pub fn connect_timeout(&self, addr: &SocketAddr, timeout: Duration) -> io::Result<()> {
         self.set_nonblocking(true)?;
-        let result = {
-            let (addr, len) = addr.into_inner();
-            let result = unsafe { c::connect(self.as_raw(), addr.as_ptr(), len) };
-            cvt(result).map(drop)
-        };
+        let result = self.connect(addr);
         self.set_nonblocking(false)?;
 
         match result {

diff --git a/library/std/src/sys_common/net.rs b/library/std/src/sys_common/net.rs
@@ -226,9 +226,7 @@ impl TcpStream {
         init();
 
         let sock = Socket::new(addr, c::SOCK_STREAM)?;
-
-        let (addr, len) = addr.into_inner();
-        cvt_r(|| unsafe { c::connect(sock.as_raw(), addr.as_ptr(), len) })?;
+        sock.connect(addr)?;
         Ok(TcpStream { inner: sock })
     }